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Our Favourite French Onion Soup

This traditional French onion soup is the ultimate comfort food, featuring deeply caramelised onions simmered in a rich, savoury broth. The secret lies in the slow-cooking process, which coaxes out the natural sweetness of the onions before they are deglazed with dry white wine. Topped with crusty baguette slices and a generous layer of melted Gruyère cheese, it offers a sophisticated balance of flavours and textures that is perfect for a chilly evening.

Ideal for a cosy weekend lunch or an elegant dinner party starter, this homemade soup is a staple of French bistro cooking. Using high-quality beef broth and finishing the dish with a touch of dry sherry adds a professional depth of flavour. Serve it piping hot in individual oven-safe bowls to achieve that iconic, golden cheese crust that makes this dish a perennial favourite.

Continue reading below

Ingredients for Our Favourite French Onion Soup

  • 5 tablespoons unsalted butter, divided

  • 1 tablespoon vegetable oil

  • 1.4kg Vidalia onions (about 4 medium), halved lengthwise, peeled, and thinly sliced

  • 1 teaspoon kosher salt

  • 1/2 teaspoons freshly ground black pepper

  • 1/2 teaspoons granulated sugar

  • 350ml dry white wine

  • 1450ml homemade beef broth or store-bought low-sodium beef broth

  • 10 sprigs thyme

  • 2 bay leaves

  • 1 baguette

  • 1 garlic clove, cut in half lengthwise

  • 2 teaspoons sherry, preferably Fino or Manzanilla

  • 110g Gruyère cheese, grated (about 240ml )

  • kitchen twine, six 230g or four 450g oven-safe ramekins or bowls (optional)

In a large Dutch oven or other large pot, melt 3 tablespoons butter over medium heat. Add the oil and onions; cook onions are until softened, stirring occasionally, about 15 minutes. Add the salt, pepper, and sugar; continue to cook, stirring occasionally, until onions are deep golden brown and caramelized, reducing heat slightly if onions seem to be browning too quickly, 35 to 45 minutes more.

Add wine and raise heat to high. Cook until almost all liquid has evaporated, 8 to 10 minutes.

Tie thyme and bay leaves into a bundle with twine. Add broth and herb bundle to pot with onions. Bring to a boil, reduce to a simmer, and cook, uncovered, until broth is thickened and flavorful, 20 to 30 minutes. Remove from heat and whisk in remaining 2 tablespoons butter. Taste and adjust seasoning.

Heat the grill. Cut two 1/2-inch baguette slices for every serving of soup. Place baguette slices on a rimmed baking sheet and toast in oven until crisp and dry but not browned, about 1 minute per side. Rub one side of each toast with the garlic clove and set aside.

Place ramekins or ovensafe bowls on a rimmed baking sheet, add 1/2 teaspoons of sherry to the bottom of each, and ladle soup on top. Top each serving of soup with two garlic-rubbed toasts. Divide cheese among the servings, covering the bread and some of the soup. Carefully transfer baking sheet to oven and grill until cheese is melted and bubbling, 4 to 8 minutes. (Alternatively, if using regular soup bowls: Top each garlic-rubbed toast with some cheese and return to grill to melt, about 2 minutes more. Divide sherry and soup among bowls, sprinkle with remaining cheese, and top each serving with two cheese toasts.)

Disclaimer

While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.

Article history

The information on this page is peer reviewed by qualified clinicians.

  • 28 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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